CN105814129A

CN105814129A - Rubber composition for tires and pneumatic tire

Info

Publication number: CN105814129A
Application number: CN201480067732.0A
Authority: CN
Inventors: 榊俊明; 皆越亮; 横山结香
Original assignee: Sumitomo Rubber Industries Ltd
Current assignee: Sumitomo Rubber Industries Ltd
Priority date: 2013-12-26
Filing date: 2014-11-27
Publication date: 2016-07-27
Anticipated expiration: 2034-11-27
Also published as: WO2015098416A1; US9732165B2; EP3075774B1; US20160297897A1; CN105814129B; EP3075774A4; JP6199733B2; EP3075774A1; JP2015124308A

Abstract

The present invention provides: a rubber composition for tires which has various properties such as low fuel consumption, processability, thermal aging resistance, wear resistance, wet grip performance, on-snow/ice performance and steering stability improved in a balanced manner; and a pneumatic tire which is produced using this rubber composition. The present invention relates to a rubber composition for tires, which contains: a modified natural rubber that is highly purified and is adjusted to have a pH of 2-7; a carbon black and/or a white filler; and a silane coupling agent represented by formula (S1). (In the formula, R1001 represents a monovalent group selected from among -Cl, -Br, -OR1006, -O(O=)CR1006, -ON=CR1006R1007, -ON=CR1006R1007, -NR1006R1007 and -(OSiR1006R1007)h(OSiR1006R1007R1008) (wherein R1006, R1007 and R1008 may be the same as or different from each other, and each represents a hydrogen atom or a monovalent hydrocarbon group having 1-18 carbon atoms; and h is a number having an average value of 1-4); R1002 represents R1001, a hydrogen atom or a monovalent hydrocarbon group having 1-18 carbon atoms; R1003 represents R1001, R1002, a hydrogen atom or a -[O(R1009O)j]0.5- group (wherein R1009 represents an alkylene group having 1-18 carbon atoms; and j represents an integer of 1-4); R1004 represents a divalent hydrocarbon group having 1-18 carbon atoms; R1005 represents a monovalent hydrocarbon group having 1-18 carbon atoms; and x, y and z represent numbers satisfying the relational expressions x + y + 2z = 3, 0 <= x <= 3, 0 <= y <= 2 and 0 <= z <= 1.).

Description

Rubber composition for tire and pneumatic tire

Technical field

The present invention relates to a kind of rubber composition for tire and the pneumatic tire formed by described rubber composition.

Background technology

In recent years, the surge of fuel price and the introducing of environmental regulations create the need of the tire for high fuel efficiency Ask, and need the tyre surface fuel efficiency going far towards fuel economy higher.Because major part tyre surface comprises natural rubber, So also needing to improve the fuel economy of natural rubber, thus improve whole tire.

Such as, patent document 1 discloses that the modification of natural rubber to improve fuel economy, wherein, by natural rubber breast Glue mixes with surfactant and washs.But, although protein and gel content can be reduced to a certain degree by the method, But desired level cannot be reduced to, and expect the further reduction of tan δ.Additionally, also need to resistance to for tyre rubber Heat aging and other performance.But, the method for patent documentation 1 is not provided that enough thermostabilitys, and existence ensures simultaneously Fuel economy and the Improvement requirement of heat-resistant aging.

Natural rubber has Mooney viscosity more higher than other synthetic rubber, and poor in processability.Generally, before use, Being mixed with peptizer by natural rubber and mastication, thus reduce Mooney viscosity, this causes bad productivity ratio.Additionally, because element The strand of natural rubber has been cut off in refining, and the natural rubber generated loses the original high-molecular-weight poly of natural rubber unfortunately Compound characteristic, the best fuel economy, wearability and rubbery intensity.

Meanwhile, many tires now have the double-decker being made up of tread base and tread cap.Expect conduct The tread cap of the assembly directly contacted with road surface has the performance with various environments match and wearability.For at summer tire In use, it is desirable to it has wet earth-catching property especially, and for without following closely the use in anti-skidding winter tire, then expects that it is special There is earth-catching property such as ice snow performance.Additionally, along with the improvement of automotive performance and the exploitation of road network, form intraware Tread base be also required to give the control stability that tire improves, particularly at the operation stabilization of improvement of period of running at high speed Property.

As discussed above, it is desired to a kind of rubber composition for tire, it is in performance such as fuel economy, processability, heat-resisting Obtain in aging, wearability, wet earth-catching property, ice snow performance and control stability and further improve.

Reference listing

Patent documentation

Patent documentation 1:JP 3294901 B

Summary of the invention

Technical problem

It is contemplated that in solving the problems referred to above, and provide rubber composition for tire and by described rubber composition shape The pneumatic tire become, described rubber composition for tire presents at performance such as fuel economy, processability, heat-proof aging Property, balance in wearability, wet earth-catching property, ice snow performance and control stability improves.

The method of solution problem

The present invention relates to a kind of rubber composition for tire, it comprises: pH adjusts the highly purified modified sky to 2～7 So rubber；At least one in white carbon black or white filler；And the silane coupler shown in following formula (S1):

Wherein, R¹⁰⁰¹Represent selected from the univalent perssad of lower group :-Cl ,-Br ,-OR¹⁰⁰⁶,-O (O=) CR¹⁰⁰⁶,-ON= CR¹⁰⁰⁶R¹⁰⁰⁷,-ON=CR¹⁰⁰⁶R¹⁰⁰⁷、-NR¹⁰⁰⁶R¹⁰⁰⁷, and-(OSiR¹⁰⁰⁶R¹⁰⁰⁷)_h(OSiR¹⁰⁰⁶R¹⁰⁰⁷R¹⁰⁰⁸), wherein, R¹⁰⁰⁶、R¹⁰⁰⁷, and R¹⁰⁰⁸It is same to each other or different to each other, and each represents hydrogen atom or C1-C18 monovalent hydrocarbon, and h Represent the numeral that meansigma methods is 1～4；R¹⁰⁰²Represent R¹⁰⁰¹, hydrogen atom or C1-C18 monovalent hydrocarbon；R¹⁰⁰³Represent R¹⁰⁰¹、R¹⁰⁰²、 Hydrogen atom or group :-[O (R¹⁰⁰⁹O)_j]_0.5-(wherein, R¹⁰⁰⁹Represent C1-C18 alkylidene, and j represent 1～4 whole Number)；R¹⁰⁰⁴Represent C1-C18 bivalent hydrocarbon radical；R¹⁰⁰⁵Represent C1-C18 monovalent hydrocarbon；Further, x, y and z are to meet following relation Numeral: x+y+2z=3,0≤x≤3,0≤y≤2 and 0≤z≤1.

Preferably, modified natural rubber obtains by the following method: removes the non-rubber component in natural rubber, uses subsequently Acid compound processes, and the pH of modified natural rubber is 2～7.

Preferably, modified natural rubber obtains by the following method: the caoutchouc latex of washing saponification, and uses acidification Compound processes scrubbed saponification caoutchouc latex, and the pH of modified natural rubber is 2～7.

Preferably, modified natural rubber obtains by the following method: washing deproteinized natural rubber latex, and uses acidification Compound processes scrubbed deproteinized natural rubber latex, and the pH of modified natural rubber is 2～7.

Preferably, the phosphorus content of modified natural rubber is below 200ppm.

Preferably, the nitrogen content of modified natural rubber is below 0.15 mass %.

Preferably, pH measures by the following method: modified natural rubber is cut into the square print of every limit at most 2mm, Described print is immersed in distilled water, the print impregnated with microwave irradiation, to carry out extracting at 90 DEG C 15 minutes, and uses PH meter measures produced dipping water.

Preferably, the heat-proof aging sex index of modified natural rubber is 75～120%, and described heat-proof aging sex index is passed through Below equation is defined based on the Mooney viscosity ML (1+4) at 130 DEG C measured according to JIS K6300:2001-1,

Heat-proof aging sex index (%)=(at 80 DEG C, the Mooney of the modified natural rubber that heat treatment measured after 18 hours glues Degree)/(Mooney viscosity of the modified natural rubber before heat treatment) × 100

The preferred silicon dioxide of described white filler.

Preferably, rubber composition comprises SBR styrene butadiene rubbers or polybutadiene rubber.

Preferably, described modified natural rubber prepares without mastication.

Another aspect of the present invention relates to pneumatic tire, and it is formed by described rubber composition for tire.

The good result of invention

The rubber composition for tire of the present invention comprises pH and is adjusted to highly purified modified natural rubber, the white carbon black of 2～7 And/or white filler and specific silane coupler.This rubber composition for tire achieves at performance such as fuel economy Property, processability, heat-resistant aging, wearability, wet earth-catching property, balance in ice snow performance and control stability improve.

Detailed description of the invention

The rubber composition for tire of the present invention comprises pH and is adjusted to highly purified modified natural rubber, the white carbon black of 2～7 And/or white filler and specific silane coupler.

Modified natural rubber is through highly purified, and the pH value of modified natural rubber is adjusted to 2～7.

Modified natural rubber carries out highly purified by removing non-rubber component such as protein and phospholipid；Further, The pH value of modified natural rubber controls as suitably value.This modified natural rubber improves processability, fuel economy, wear-resisting Property, wet earth-catching property, ice snow performance and control stability.When being removed from non-rubber component or when rubber in When existing alkalescence or highly acid, rubber is easily degraded.But, by the pH of rubber is adjusted in preset range, it is possible to suppress Molecular weight during storage reduces, and is derived from good heat-resistant aging.This makes it possible to prevent rubber physical performance Deterioration, and improve the filler dispersibility during kneading, thus improve processability, fuel economy, wearability, wet adherence properties Energy, ice snow performance, the balance of control stability.In addition to modified natural rubber, the invention still further relates to specific silane even The addition of connection agent.This collaborative balance improving above-mentioned performance, and thus significantly improve the balance of performance.

Word " highly purified " refers to the impurity such as phosphoric acid and albumen in addition to natural polyisoprenoids component Matter removes.Natural rubber is similar to that the structure that wherein isoprenoid component is covered by these impurity.By going remove impurity Matter, it is believed that the structure of isoprenoid component is varied so that the interaction with compounding ingredient is changed, thus reduce energy and damage Consumption, and improve durability, thus prepare the rubber composition of better quality.

It can be any modified natural rubber that pH is adjusted to the highly purified modified natural rubber of 2～7, and it is by reducing The amount of non-rubber component carries out highly purified, and has the pH of 2～7.Specific example includes: (1) modified natural rubber, its By removing the non-rubber component in natural rubber, it is processed to obtain with acid compound subsequently, and it has 2～7 PH；(2) modified natural rubber, it is by washing saponification caoutchouc latex, and processes scrubbed soap with acid compound Change caoutchouc latex to obtain, and it has the pH of 2～7；And (3) modified natural rubber, it is by washing deproteinization Caoutchouc latex, and with acid compound process scrubbed deproteinized natural rubber latex obtain, and its have 2～ The pH of 7.

As it has been described above, modified natural rubber can be prepared by such as following method: natural with washing saponification such as distilled water Elastomer latex or deproteinized natural rubber latex, and process scrubbed latex with acid compound.It may be necessary use Acid compound is processed to be adjusted to pH acidic side, and makes this pH pH less than the distilled water used in washing..Distillation The pH of water is not the most 7.00, but about 5～6.If using the distilled water with this pH value, then be necessary to use acidification Compound is processed to this pH value is reduced to the pH value than pH 5～6 more slant acidity.In particular, it is preferred that use acid compound Process, thus the value of the pH low 0.2～2 of water used in being reduced to pH wash than water.

The pH of modified natural rubber is 2～7, preferably 3～6, more preferably 4～6.When the pH value of modified natural rubber is adjusted to Time in above-mentioned scope, the reduction of heat-resistant aging can be prevented and significantly improve above-mentioned performance.Preferably, modified natural rubber PH measures by the following method: rubber is cut into the square print of every limit at most 2mm, described print is immersed in distilled water In, at 90 DEG C, irradiate the print 15 minutes of dipping for extracting with microwave, and measure produced dipping water with pH meter.Specifically Ground is said, pH determines according to the method described the most in an embodiment.About extraction, use one hour of supersound washing device etc. Extraction can not extract water-soluble component inside rubber completely, and thus can not accurately show the pH of inside.On the contrary, originally Inventor finds can be illustrated the actual performance of rubber by the extraction of above-mentioned technology.

Modified natural rubber by arbitrary various methods, include that method (1)～(3) carry out highly purified.Such as, modified Preferred below the 200ppm of phosphorus content, more preferably below 150ppm of natural rubber.When phosphorus content is more than 200ppm, during storage Mooney viscosity increases, so that processability deteriorates, and tan δ increases, so that fuel economy can not be improved.Phosphorus content can lead to Cross conventional method such as ICP emission analysis method to measure.Speculate that phosphorus derives from the phospholipid in natural rubber.

In the case of modified natural rubber contains artificial antioxidant, modified natural rubber is soaked under room temperature (25 DEG C) Stain is in acetone after 48 hours, below the nitrogen content of this modified natural rubber preferably 0.15 mass %, more preferably 0.1 mass % with Under.When nitrogen content is more than 0.15 mass %, during storage, Mooney viscosity increases, so that processability deteriorates, and improves fuel Economy not sufficiently effective.Do not contain the height of natural antioxidant component (it is considered as natural in natural rubber comprising) The natural rubber of degree purification can deteriorate during long term storage.In order to solve this problem, artificial antioxidant sometimes can be added. After being removed by the artificial antioxidant in rubber with acetone extract, measure nitrogen content.Nitrogen content can by conventional method such as Kjeldahl's method (Kjeldahl method) or use trace blood urea/nitrogen analyzer are measured.Nitrogen comes from protein and aminoacid.

The Mooney viscosity ML (1+4) at 130 DEG C that modified natural rubber measures according to JIS K6300:2001-1 is preferred Less than 75, more preferably 40～75, more preferably 45～75, particularly preferred 50～70, most preferably 55～65.Mooney viscosity is less than 75 Modified natural rubber need not mastication, and this typically required before rubber is mediated.Just can prepare without mastication operation Modified natural rubber can suitably serve as the mixing material (compounding material) preparing rubber composition.Separately On the one hand, the Mooney viscosity modified natural rubber more than 75 needs mastication before use, and this tends to lead to shortcoming such as needs Special equipment, electric energy or hot loss of energy etc..

The heat-proof aging sex index preferably 75～120% of modified natural rubber, wherein, described heat-proof aging sex index is passed through Following formula is defined based on the Mooney viscosity ML (1+4) at determined as outlined above 130 DEG C,

The heat-proof aging sex index more preferably 80～115% defined by above formula, even more preferably from 85～110%.Although report Road for assessing the various methods of the heat-resistant aging of rubber, but, heat-resistant aging is such as in tire production or validity period Between heat-resistant aging can be by the Mooney viscosity ML (1+4) measured at before and after 18 hours 130 DEG C of heat treatment at 80 DEG C Rate of change accurately assess.When heat-proof aging sex index falls within the above-described range, it is thus achieved that outstanding heat-proof aging Property, and significantly improve the balance of above-mentioned performance.

PH adjust to 2～7 highly purified modified natural rubber such as rubber (1)～(3) can be by below such as Prepared by preparation method 1 or 2.Preparation method 1 includes: caoutchouc latex carries out step 1-1 of saponification, the washing natural rubber of saponification Step 1-2 of latex glue and process step 1-3 of latex with acid compound.Preparation method 2 includes: to natural rubber breast Glue carries out step 2-1 of deproteinization process, step 2-2 of washing deproteinized natural rubber latex and uses at acid compound Step 2-3 of reason latex.

[preparation method 1]

(step 1-1)

Step 1-1 includes caoutchouc latex is carried out saponification.The phospholipid in rubber and protein have been decomposed in this process, by This provides the saponification caoutchouc latex of the non-rubber component containing reduction amount.

Caoutchouc latex is the resin as natural rubber trees such as Hevea and gathers.It contains and includes The component of water, protein, lipid, inorganic salt and rubber components.Gel component in rubber is considered to be derived from rubber various The complex (complex) of impurity.In the present invention, the caoutchouc latex used can be to be taken from SANYE by rubber tapping The lactogenesis glue (fresh latex) of gum or process via centrifugal treating or creaming and concentrate the concentrated latex (example prepared Such as purification latex, by adding ammonia in a usual manner and the high ammonia latex that obtains or stable with zinc oxide, TMTD and ammonia LATX latex).

Suitably, saponification can be by such as institute's public affairs in JP 2010-138359 A and JP 2010-174169 A The extraction of root is carried out.Specifically, saponification can be carried out by such as following method.

Mixture by adding alkali and surfactant alternatively in caoutchouc latex, and can made a reservation for by saponification At a temperature of stand special time carry out.If desired, can be stirred.

Alkali used in saponification is preferably but not limited to sodium hydroxide, potassium hydroxide etc..Surfactant non-limiting Example includes known anionic surfactant, nonionic surfactant and amphoteric surfactant, the most poly- Oxygen vinyl alkyl ether sulfate.Suitably from anionic surfactants such as polyoxyethylene alkyl ether sulfate salt, this be by Saponification can be realized in the case of not curing rubber well in it.In saponification, suitably select alkali and surfactant Amount and the persistent period of saponification and temperature.

(step 1-2)

Step 1-2 includes the saponification caoutchouc latex obtained in washing step 1-1.Non-rubber component is removed by washing Such as protein.

Such as, step 1-2 can be carried out by the following method: the saponification caoutchouc latex obtained in congealing step 1-1, Thus prepare condensation rubber (coagulated rubber), process with alkali compounds and condense rubber, be washed out being obtained Rubber.Specifically, after producing condensation rubber, it is diluted water-soluble component is transferred to aqueous phase with water, then goes Except water, non-rubber component thus can be removed.Further, process with alkali compounds and condense rubber, such that it is able to will be solidifying It is captured on the non-rubber component within rubber during knot and carries out re-dissolved.Therefore, it can remove strength be attached to condense rubber Interior non-rubber component such as protein.

Typical coagulation method may include that interpolation acid such as formic acid, acetic acid or sulphuric acid thus regulates pH, and alternatively Add high polymer coagulant further.This does not produce big coagula, but produce diameter be about less than 1 to several mm and Granulated rubber between 20mm, then, by being processed to fully remove the protein in this rubber with alkali compounds Deng.PH preferably adjusts in the range of 3.0～5.0, more preferably 3.5～4.5.

The example of high polymer coagulant includes: cation polymeric flocculant, the most poly-((methyl) acrylic acid dimethylamino Base ethylacrylate methyl chloride quaternary)；Anionic polymer flocculant, the most poly-(acrylates)；Nonionic high polymer coagulant, Such as polyacrylamide；And Amphiphatic high polymer coagulant, such as (methyl) acrylate methyl chloride season Salt and the copolymer of acrylates.Can suitably select the amount of high polymer coagulant.

Then, thus obtained condensation rubber alkali compounds processes.Alkali compounds is not particularly limited.Alkalescence nothing Machine compound is suitable, this is because they can remove protein etc..

The example of alkaline inorganic compound includes: metal hydroxides, such as alkali metal hydroxide and alkaline-earth metal Hydroxide；Metal carbonate, such as alkali carbonate and alkaline earth metal carbonate；Alkali metal bicarbonate salt, such as alkali gold Belong to bicarbonate；Metal phosphate, such as alkali metal phosphate ester；Metal acetate, such as alkali metal acetate；Metal hydride Thing, such as alkali metal hydride；And ammonia.

The example of alkali metal hydroxide includes: Lithium hydrate, sodium hydroxide and potassium hydroxide.Alkaline-earth metal hydroxide The example of thing includes: magnesium hydroxide, calcium hydroxide and barium hydroxide.The example of alkali carbonate includes: lithium carbonate, carbonic acid Sodium and potassium carbonate.The example of alkaline earth metal carbonate includes: magnesium carbonate, calcium carbonate and brium carbonate.Alkali metal hydrogen carbonate The example of salt includes: lithium bicarbonate, sodium bicarbonate and potassium bicarbonate.The example of alkali metal phosphate includes: sodium phosphate and Dibastic sodium phosphate.The example of alkali metal acetate includes: sodium acetate and potassium acetate.The example of alkali metal hydride includes: hydrogenation Sodium and hydrofining.

In these, preferably metal hydroxides, metal carbonate, alkali metal bicarbonate salt, metal phosphate and ammonia；More Preferred alkali metal carbonate, alkali metal bicarbonate salt and ammonia；Even more preferably from sodium carbonate or sodium bicarbonate.Each alkali compounds Can be used alone, or be used in combination.

By any method that condensation rubber can be made to contact with alkali compounds, to process with alkali compounds to condense rubber Glue.Example includes: will condense rubber impregnated method in alkali compounds aqueous solution and is sprayed by alkali compounds aqueous solution Mist is in the method condensed on rubber.Alkali compounds aqueous solution can be by diluting and dissolving alkali compounds system in water Standby.

Aqueous solutions based on 100 mass %, more than the amount of alkali compounds preferably 0.1 mass %, more preferably 0.3 mass % Above.When its amount is less than 0.1 mass %, it is impossible to remove isolating protein fully.The amount of alkali compounds preferably 10 mass % with Under, below more preferably 5 mass %.When its amount is more than 10 mass %, although with the most substantial amounts of alkali compounds, but quilt The amount of the protein decomposed will not increase, and efficiency trends towards bad.

Preferably, the pH of the aqueous solution of alkali compounds is 9～13.In view for the treatment of effeciency, pH more preferably 10～12.

Can suitably select treatment temperature, and preferably 10 DEG C～50 DEG C, more preferably 15 DEG C～35 DEG C.Additionally, process holds The continuous time is usually more than 1 minute, preferably more than 10 minutes, more preferably more than 30 minutes.When Duration Ratio 1 minute in short-term, The effect of the present invention can not be realized well.Although its upper limit does not limit, it is contemplated that productivity ratio, persistent period preferably 48 Below hour, more preferably less than 24 hours, even more preferably from less than 16 hours.

After processing with alkali compounds, wash.It is non-that this process makes in duration of coagulation is captured on rubber Rubber components such as protein is sufficiently removed, and simultaneously so that condensing rubber inside and these condensation rubber surfaces Present on alkali compounds be sufficiently removed.Especially, as described later, remove in washing step and remain in whole rubber Alkali compounds so that all rubber are fully subjected to the process that acid compound is carried out.Therefore, the pH of not only rubber surface And the pH within rubber is adjusted to 2～7.

The method of the alkali compounds by can fully remove non-rubber component and be included in whole rubber, Ke Yishi When washing.Such as, washing can be carried out by the following method: wherein, and rubber components dilutes in water and washs, and leads to subsequently Cross centrifugal treating or subsequently by standing so that rubber is floating, the most only discharge aqueous phase thus collect rubber components.Washing follows The number of times of ring can arbitrarily select, as long as the amount of the amount of non-rubber component such as protein and alkali compounds is reduced to expect water Flat.In the case of repeated washing circulates, more than the number of times of cycles of washing preferably 3 (3 times), more than more preferably 5 (5 times), more excellent Selecting more than 7 (7 times), this cycles of washing is made up of following steps: add the water of 1000ml, stirring mixing in the dry rubber substance of every 300g Thing, then removes water.

Preferably wash, until the nitrogen content that the phosphorus content of rubber is below 200ppm and/or rubber is 0.15 matter Amount below %.During when carrying out washing so that fully removing phospholipid and protein, improve above-mentioned performance.

(step 1-3)

Step 1-3 includes processing, with acid compound, the scrubbed rubber obtained in step 1-2.As it has been described above, at this The pH of whole rubber is adjusted to 2～7, thus provide the modified natural rubber that above-mentioned performance is outstanding by reason.Although with alkalescence chemical combination The process of thing etc. and cause heat-resistant aging trend towards lower, but this problem will be prevented also by the additional treatments of acid compound Good heat-resistant aging is provided.

The non-limitative example of acid compound includes: mineral acid, such as hydrochloric acid, nitric acid, sulphuric acid, phosphoric acid, polyphosphoric acid, partially Phosphoric acid, boric acid (boric acid), boric acid (boronic acid), sulfanilic acid and sulfamic acid；And organic acid, such as Formic acid, acetic acid, hydroxyacetic acid, oxalic acid, propanoic acid, malonic acid, succinic acid, adipic acid, maleic acid, malic acid, tartaric acid, Fructus Citri Limoniae Acid, benzoic acid, phthalic acid, M-phthalic acid, 1,3-propanedicarboxylic acid, gluconic acid, lactic acid, aspartic acid, glutamic acid, salicylic acid, Methanesulfonic acid, itaconic acid, benzenesulfonic acid, toluenesulfonic acid, naphthalenedisulfonic acid, trifluoromethayl sulfonic acid, styrene sulfonic acid, trifluoroacetic acid, bar ratio Appropriate acid, acrylic acid, methacrylic acid, cinnamic acid, 4-HBA, amino benzoic Acid, naphthalenedisulfonic acid, hydroxy benzenesulfonic acid, first Benzenesulfinic acid, benzenesulfinic acid, α-resorcylic acid, β-resorcylic acid, γ-resorcylic acid, gallic acid, Resina garciniae phenolic acid (phloroglycine), sulfosalicylic acid, ascorbic acid, arabo-ascorbic acid and diphenoliac acid.Preferred acetic acid, sulfur in these Acid, formic acid etc..Each acid compound can be used alone, or is used in combination.

Rubber can be condensed with acid treatment by any method that condensation rubber can be made to contact with acid compound.Example Attached bag includes: will condense rubber impregnated method in acid compound aqueous solution and is sprayed at by acid compound aqueous solution Condense the method on rubber.Acid compound aqueous solution can be prepared by diluting in water and dissolving acid compound.

Described aqueous solutions based on 100 mass %, although the amount of acid compound is not particularly limited, but lower limit is preferred It is more than 0.1 mass %, more preferably 0.3 mass %, and below the upper limit preferably 15 mass %, below more preferably 10 mass %, more Below preferably 5 mass %.When equivalent falls within the above-described range, it is possible to obtain good heat-resistant aging.

Can suitably select treatment temperature, and preferably 10 DEG C～50 DEG C, more preferably 15 DEG C～35 DEG C.Additionally, process holds The continuous time is usually more than 3 seconds, preferably more than 10 seconds, more preferably more than 30 seconds.When Duration Ratio 3 seconds in short-term, it is impossible to fully Neutralize rubber, thus can not realize the effect of the present invention well.Although the upper limit does not limit, it is contemplated that productivity ratio, hold Preferably less than 24 hours continuous time, more preferably less than 10 hours, even more preferably from less than 5 hours.

Processing such as by being immersed in acid compound aqueous solution, pH is preferably adjusted to less than 6.

This neutralization causes outstanding heat-resistant aging.The upper limit of pH more preferably less than 5, more preferably less than 4.5.Although depending on Lower limit in the persistent period pH of dipping is not particularly limited, but because too strong acidity can cause the degraded of rubber, and meeting Waste water is made to process complexity, it is advantageous to be more than 1, more preferably more than 2.For example, it is possible to by condensation rubber is stayed acid Property compound water solution carries out impregnation process.

After being like this, remove the compound used in processing with acid compound, then can suitably wash Treated condensation rubber.Can wash in the same way as described above.Such as, by repeated washing, nonrubber The amount of component can reduce further and be adjusted to desired level.Additionally, the condensation obtained after processing with acid compound Rubber can be flake etc. with the extruding of such as roll squeezer.Extruding condense rubber additional step make condense rubber surface and Inside has uniform pH, and the rubber obtained has desired performance.Wash and/or after extrusion step optionally carrying out, The rubber obtained is milled on crepe machine and is dried, and is derived from modified natural rubber.Can be dried by any way, Such as by using the conventional dryers for being dried TSR, such as cart type drying machine (trolley dryer), vacuum drying Machine, dried-air drier or cylindrical drier.

[production method 2]

(step 2-1)

Step 2-1 includes caoutchouc latex deproteinization.This process manufactures deproteinized natural rubber latex, and it does not contains There is non-rubber component such as protein.The caoutchouc latex used in step 2-1 can be same as described above.

Deproteinization processes can be by going any known method of isolating protein to carry out.Typical method includes to sky So elastomer latex interpolation proteolytic enzyme, thus decomposing protein.

The proteolytic enzyme used in deproteinization processes can be (but are not limited to) any being derived from the enzyme of antibacterial, being derived from The enzyme of mycete and be derived from the enzyme of yeast.Specifically, it is possible to use protease, peptidase, cellulase, pectase, fat One or combinations thereof in enzyme, esterase, amylase etc..

Relative to the solid in caoutchouc latex of every 100 mass parts, the amount of proteolytic enzyme preferably 0.005 mass More than Fen, more than more preferably 0.01 mass parts, more than more preferably 0.05 mass parts.Proteolytic enzyme is may result in less than the amount of lower limit React insufficient.

In deproteinization processes, surfactant can also add together with proteolytic enzyme.Surfactant Example includes: anionic surfactant, cationic surface active agent, nonionic surfactant and both sexes table Face activating agent.

(step 2-2)

Step 2-2 includes the deproteinized natural rubber latex obtained in washing step 2-1.Nonrubber group is removed by washing Divide such as protein.

Such as, step 2-2 can be by being carried out as follows: the deproteinized natural rubber latex obtained in congealing step 2-1, from And prepare condensation rubber, and wash the rubber through condensing.Therefore, it can remove strength be attached to condense the nonrubber group in rubber Divide such as protein.

Mode that can be identical with in step 1-2 condenses.Further, it is also possible to carry out alternatively by alkalescence as mentioned above The process that compound is carried out.After producing condensation rubber, wash.The mode identical with step 1-2 can carry out this and wash Wash, thus remove non-rubber component such as protein and alkali compounds.For reason same as described above, preferably wash Wash, until the nitrogen content that the phosphorus content of rubber is below 200ppm and/or rubber is below 0.15 mass %.

(step 2-3)

Step 2-3 includes processing, with acid compound, the scrubbed rubber obtained in step 2-2.Not only with alkalescence chemical combination The process of thing and use the acid cure knot of a small amount of acid to trend towards reducing heat-resistant aging, this is because the final rubber obtained Water extract demonstrates alkalescence or neutrality.The enzyme in basic region with suitable pH is typically used as proteolytic enzyme, this is because They can suitable deproteinization.This enzyme reaction is usually carried out under the conditions of the alkalescence depending on optimum pH.In order to by final rubber The pH of glue is adjusted to 2～7, and in step 2-1, caoutchouc latex is preferably pH 8～11 times, more preferably enter pH 8.5～11 times Row deproteinization.Then, in condensing technique, deproteinization latex solidifies in acid condition.When only washing curing rubber with water Time, the rubber extract obtained in following extraction has the pH higher than extractant pH, and especially, this rubber demonstrates Being greatly reduced of heat-resistant aging.In contrast, when with acid compound process curing rubber, optionally followed by with alkalescence chemical combination When thing processes, it is possible to prevent the problems referred to above, and obtains good heat-resistant aging.

The identical acid compound mentioned in step 1-3 can be used.Furthermore, it is possible to by condensation rubber can be made Any method contacted with acid compound, condenses rubber with acid treatment.Example includes: will condense rubber impregnated at acid chemical combination Method in thing aqueous solution and acid compound aqueous solution is sprayed at the method condensed on rubber.Acid compound is water-soluble Liquid can be prepared by diluting in water and dissolving acid compound.

Above-mentioned aqueous solutions based on 100 mass %, although the amount of acid compound is not particularly limited, but lower limit is preferred It is more than 0.01 mass %, more preferably 0.03 mass %, and below the upper limit preferably 15 mass %, below more preferably 10 mass %, Below 5 mass %.When equivalent falls within the above-described range, it is possible to obtain good heat-resistant aging.

Can suitably select the temperature for processing and persistent period.Can be carried out this with the temperature identical with step 1-3 Process.Processing such as by being immersed in acid compound aqueous solution, pH is preferably adjusted to the scope identical with step 1-3.

After being like this, remove the compound used in processing with acid compound, then can suitably wash Treated condensation rubber.Can wash in the same manner described above.Such as, by repeated washing, non-rubber component Amount can reduce further and be adjusted to desired level.After washing completes, the rubber obtained is dried, the most permissible Obtain modified natural rubber.It is dried and can technology the most as above carry out.

In the case of the rubber composition of the present invention is used for using in the tread cap of summer tire, based on 100 matter The rubber components of amount %, more than the amount of modified natural rubber preferably 5 mass %, more than more preferably 10 mass %, even more preferably from 20 More than quality %.When this amount is less than 5 mass %, it is impossible to obtain outstanding fuel economy.The amount of modified natural rubber is the most excellent Select below 80 mass %, below more preferably 60 mass %, below 40 mass %.When this amount is more than 80 mass %, Wet earth-catching property may decline.

In the case of the rubber composition of the present invention uses in the tread cap following closely anti-skidding winter tire in nothing, based on The rubber components of 100 mass %, more than the amount of modified natural rubber preferably 5 mass %, more than more preferably 30 mass %, the most excellent Select more than 40 mass %, more than particularly preferred 50 mass %.When this amount is less than 5 mass %, it is impossible to obtain outstanding fuel warp Ji property.Below the amount of modified natural rubber further preferably 90 mass %, below more preferably 80 mass %, even more preferably from 75 mass % with Under.When this amount is more than 90 mass %, ice snow performance and wearability may decline.

In the case of the rubber composition of the present invention is used for using in tread base, rubber based on 100 mass % Component, more than the amount of modified natural rubber preferably 5 mass %, more than more preferably 30 mass %, more than 45 mass %, More than particularly preferred 60 mass %.When this amount is less than 5 mass %, it is impossible to obtain outstanding fuel economy.Modified natural rubber Below the amount of glue further preferably 90 mass %, below more preferably 80 mass %.When this amount is more than 90 mass %, control stability can Can decline.

In addition to modified natural rubber, the example of the rubber that can serve as rubber components includes: natural rubber is (unmodified ) (NR), epoxy natural rubber (ENR), polyisoprene rubber (IR), polybutadiene rubber (BR), styrene-butadiene Rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), Ethylene-Propylene-Diene rubber (EPDM), neoprene And acrylonitrile-butadiene rubber (NBR) (CR).In view of fuel economy and wet earth-catching property, preferably mix SBR.Consider To cryogenic property or durability, preferably mix BR.

The non-limitative example of SBR includes polymerisation in solution SBR (S-SBR), emulsion polymerization SBR (E-SBR) and thus makes Standby modified SBR.The example of modified SBR includes: SBR that its end of the chain and/or main chain are modified and by using tin compound Or silicon compound etc. carries out coupling and the modified SBR (such as, condensation substance, have those of branched structure) that obtains.

More than the styrene-content of SBR preferably 5 mass %, more than preferably 10 mass %, more than 20 mass %. When styrene-content is less than 5 mass %, it is impossible to obtain enough earth-catching properties or rubbery intensity.Styrene-content further preferably 60 Below quality %, below more preferably 50 mass %, below 45 mass %.When styrene-content is more than 60 mass % Time, it is impossible to obtain outstanding fuel economy.Herein, the styrene-content of SBR passes through¹H-NMR measures.

More than the contents of ethylene of SBR preferably 10 mass %, more than preferably 15 mass %, even more preferably from 20 mass % with On.When contents of ethylene is less than 10 mass %, it is impossible to obtain enough earth-catching properties or rubbery intensity.Contents of ethylene is the most excellent Select below 65 mass %, below more preferably 60 mass %, below 30 mass %.When contents of ethylene is more than 65 matter During amount %, it is impossible to obtain outstanding fuel economy.Herein, the contents of ethylene of SBR refers to the vinyl in butadiene fraction Content, it passes through¹H-NMR measures.

At rubber composition in the case of the tread cap of summer tire, rubber components based on 100 mass %, SBR Amount preferably 40 mass % more than, and more than more preferably 50 mass %.When this amount is less than 40 mass %, it is impossible to obtain enough Earth-catching property.Below the amount of SBR preferably 90 mass %, below more preferably 80 mass %.When this amount is more than 90 mass %, change Property natural rubber may not provide outstanding fuel economy.

The non-limitative example of BR includes those BR being generally used in tire industry.In order to ensure enough low temperature properties or Durability, more than the cis-content of BR preferably 70 mass %, more than more preferably 90 mass %, more than 97 mass %.

Mooney viscosity (the ML of BR₁₊₄(100 DEG C)) preferably more than 10, more preferably more than 30.When Mooney viscosity is less than 10, The dispersibility of filler trends towards declining.Mooney viscosity is preferably less than 120, and more preferably less than 80.When Mooney viscosity is more than 120 Time, it may happen that mixture incipient scorch (variable color) during extrusion processing.

The molecular weight distribution (Mw/Mn) preferably more than 1.5, more preferably more than 2.0 of BR.When Mw/Mn is less than 1.5, processing Property may decline.The Mw/Mn of BR is preferably less than 5.0, and more preferably less than 4.0.When Mw/Mn is more than 5.0, wearability and behaviour Handing stability trends towards deterioration.Mn and Mw value in the present invention is measured by the GPC relative to polystyrene standards.

At rubber composition in the case of the tread cap without the anti-skidding winter tire of nail, it is contemplated that the ice and snow needed for acquisition For upper performance, rubber components based on 100 mass %, more than the amount of BR preferably 10 mass %, more than more preferably 20 mass %, More than 30 mass %.In addition, it is contemplated that processability, below the amount of BR preferably 80 mass %, more preferably 70 mass % Hereinafter, below even more preferably from 65 mass %.

At rubber composition in the case of tread base, it is contemplated that the viewpoint of the control stability required for acquisition, Rubber components based on 100 mass %, more than the amount of BR preferably 5 mass %, more than more preferably 15 mass %.In addition, it is contemplated that Fuel economy and processability, below the amount of BR preferably 50 mass %, below more preferably 40 mass %.

The rubber composition of the present invention comprises white carbon black and/or white filler.This produces reinforcing effect.

The non-limitative example of white carbon black includes: GPF, FEF, HAF, ISAF and SAF.These white carbon blacks each can individually make With, it is also possible to it is used in combination.

N2 adsorption specific surface area (the N of white carbon black₂SA) preferably 50m²/ more than g, more preferably 60m²/ more than g.N₂SA is further preferably 300m²/ below g, more preferably 250m²/ below g, even more preferably from 200m²/ below g.Use N₂SA is less than 50m²The white carbon black of/g tends to In can not fully produce reinforcing effect.Use N₂SA is more than 300m²The white carbon black of/g trends towards reducing fuel economy.

The N2 adsorption specific surface area of white carbon black is measured by method A according to JIS K 6217.

Relative to the rubber components of every 100 mass parts, more than the amount of white carbon black preferably 1 mass parts, more preferably 2 mass parts with On.Below the amount of white carbon black preferably 150 mass parts, below more preferably 100 mass parts.When this amount falls within the above-described range, permissible Obtain good fuel economy, good wearability and good control stability.

The example of white filler includes those generally used in rubber industry, such as, silicon dioxide, calcium carbonate, Muscovitum Such as sericite, aluminium hydroxide, magnesium oxide, magnesium hydroxide, clay, Talcum, aluminium oxide and titanium oxide.In view of fuel warp Ji property, preferably silicon dioxide.

The non-limitative example of silicon dioxide includes dry silicon dioxide (anhydrous silicic acid) and wet silicon dioxide (silicate hydrate). The wettest silicon dioxide, because it has many silanol groups.

N2 adsorption specific surface area (the N of silicon dioxide₂SA) it is 40m²/ more than g, more preferably 50m²/ more than g, even more preferably from 100m²/ more than g, particularly preferred 150m²/ more than g.Work as N₂SA is less than 40m²During/g, the Zhong Qiangdu that draws after sulfuration trends towards reducing. The N of silicon dioxide₂SA further preferably 500m²/ below g, more preferably 300m²/ below g, even more preferably from 200m²/ below g.Work as N₂SA is big In 250m²During/g, low-heat-generation performance or rubber processing trend towards reducing.The N2 adsorption specific surface area of silicon dioxide passes through basis The BET method of ASTM D3037-81 measures.

Relative to the rubber components of every 100 mass parts, more than the amount of white filler or silicon dioxide preferably 5 mass parts, more More than preferably 20 amount parts, more than 30 mass parts, more than particularly preferred 40 mass parts.When this amount is less than 5 mass parts, Insufficient low-heat-generation performance may be obtained.Below the amount of white filler or silicon dioxide further preferably 200 mass parts, more preferably Below 150 mass parts, below 130 mass parts.When this amount is more than 200 mass parts, filler is not easy to be dispersed in rubber In glue, and rubber processing trends towards deteriorating.

In the rubber composition of the present invention, relative to the rubber components of every 100 mass parts, white carbon black and silica filler Total amount preferably 5 mass parts more than, more than more preferably 10 mass parts, more than 20 mass parts.This total amount is preferred Below 150 mass parts, below more preferably 120 mass parts.When total amount falls within the above-described range, it is possible to obtain good fuel Economy, good wearability, good wet earth-catching property, good ice snow performance and good control stability.

The rubber composition of the present invention comprises the silane coupler shown in below general formula (S1).Shown in formula (S1) silane coupled Agent and above-mentioned modified natural rubber be applied in combination the balance significantly improving above-mentioned performance.

In formula, R¹⁰⁰¹Represent selected from the univalent perssad of lower group :-Cl ,-Br ,-OR¹⁰⁰⁶,-O (O=) CR¹⁰⁰⁶,-ON= CR¹⁰⁰⁶R¹⁰⁰⁷,-ON=CR¹⁰⁰⁶R¹⁰⁰⁷、-NR¹⁰⁰⁶R¹⁰⁰⁷, and-(OSiR¹⁰⁰⁶R¹⁰⁰⁷)_h(OSiR¹⁰⁰⁶R¹⁰⁰⁷R¹⁰⁰⁸), wherein, R¹⁰⁰⁶、R¹⁰⁰⁷, and R¹⁰⁰⁸It is same to each other or different to each other, and each represents hydrogen atom or C1-C18 monovalent hydrocarbon, and h Represent that meansigma methods is the numeral of 1-4；R¹⁰⁰²Represent R¹⁰⁰¹, hydrogen atom or C1-C18 monovalent hydrocarbon；R¹⁰⁰³Represent R¹⁰⁰¹、R¹⁰⁰², hydrogen Atom or group :-[O (R¹⁰⁰⁹O)_j]_0.5-(wherein, R¹⁰⁰⁹Represent C1-C18 alkylidene, and j represents the integer of 1-4)； R¹⁰⁰⁴Represent C1-C18 bivalent hydrocarbon radical；R¹⁰⁰⁵Represent C1-C18 monovalent hydrocarbon；And x, y and z are the numbers meeting following relation Word: x+y+2z=3,0≤x≤3,0≤y≤2 and 0≤z≤1.

Preferably, the R in formula (S1)¹⁰⁰⁵、R¹⁰⁰⁶、R¹⁰⁰⁷And R¹⁰⁰⁸It is each independently selected from the group being made up of following group: C1-C18 straight chain, ring-type or the alkyl of side chain, alkenyl, aryl and aralkyl.Additionally, it is C1-C18 monovalent hydrocarbon R¹⁰⁰²It is preferably selected from the group being made up of following group: straight chain, ring-type or the alkyl of side chain, alkenyl, aryl and aralkyl. R¹⁰⁰⁹Preferably straight chain, ring-type, the alkylidene of side chain, the alkylidene of particularly preferred straight chain.R¹⁰⁰⁴Example include: C1-C18 alkylene Base, C2-C18 alkenylene, C5-C18 cycloalkylidene, C6-C18 cycloalkyl alkylidene, C6-C18 arlydene and C7-C18 virtue are sub- Alkyl (aralkylene).Alkylidene and alkenylene can be straight or brancheds.Cycloalkylidene, cycloalkyl alkylidene, sub-virtue Base, arylmethylene alkyl each can have functional group's such as low alkyl group on ring.R¹⁰⁰⁴Preferably C1-C6 alkylidene, particularly preferably Straight-chain alkyl-sub-such as methylene, ethylidene, trimethylene, tetramethylene, pentamethylene or hexa-methylene.

R in formula (S1)¹⁰⁰²、R¹⁰⁰⁵、R¹⁰⁰⁶、R¹⁰⁰⁷And R¹⁰⁰⁸Example include methyl, ethyl, n-pro-pyl, isopropyl, Normal-butyl, isobutyl group, sec-butyl, the tert-butyl group, amyl group, hexyl, octyl group, decyl, dodecyl, cyclopenta, cyclohexyl, ethylene Base, acrylic, pi-allyl, hexenyl, octenyl, cyclopentenyl, cyclohexenyl group, phenyl, tolyl, xylyl, naphthyl, benzene Methyl, phenethyl and naphthyl methyl.

In formula (S1) as R¹⁰⁰⁹The example of straight-chain alkyl-sub-include: methylene, ethylidene, positive propylidene, just sub- Butyl and hexylidene, the example of branched alkylidene includes isopropylidene, isobutylene and 2-methyl propylene simultaneously.

The object lesson of the silane coupler shown in formula (S1) includes: 3-caproyl sulfopropyl triethoxysilane, 3- Octanoylthio propyl-triethoxysilicane, 3-capryl sulfopropyl triethoxysilane, 3-lauroyl sulfopropyl three Ethoxysilane, 2-caproyl thio-ethyl triethoxysilane, 2-Octanoylthio ethyl triethoxysilane, 2-capryl Thio-ethyl triethoxysilane, 2-lauroyl thio-ethyl triethoxysilane, 3-caproyl sulfopropyl trimethoxy Silane, 3-Octanoylthio propyl trimethoxy silicane, 3-capryl sulfopropyl trimethoxy silane, 3-lauroyl sulfur generation Propyl trimethoxy silicane, 2-caproyl thio-ethyl trimethoxy silane, 2-Octanoylthio ethyl trimethoxy silane, 2- Capryl thio-ethyl trimethoxy silane and 2-lauroyl thio-ethyl trimethoxy silane.In these, in order to same Time obtain processability and fuel economy, particularly preferred 3-Octanoylthio propyl-triethoxysilicane is (purchased from Momentive The NXT silane of Performance Materials company).Each silane coupler can be used alone, or two or more combination Use.

Relative to white carbon black and the total amount of white filler of every 100 mass parts, the amount of silane coupler preferably 0.1 mass parts with On, more than more preferably 1 mass parts, more than 2 mass parts, more than particularly preferred 3 mass parts.When this amount is less than 0.1 matter During amount part, resistance to rolling trends towards increasing.Below the amount of silane coupler further preferably 20 mass parts, more preferably 16 mass parts with Under, below 12 mass parts.When this amount is more than 20 mass parts, processability trends towards reducing on the contrary.

Rubber composition preferably comprises oil as plasticizer.This makes it possible to be adjusted to hardness suitable low water-mark, by The processability that this offer is good.The non-limitative example of the oil that can use includes conventional oil, and it includes operation oil, such as paraffin Operation oil, aromatic series operation oil and napthenic process oil；Low PCA operation oil, such as TDAE and MES；Vegetable oil lipoprotein；With And above-mentioned mixture.In terms of wearability and durability, optimization aromatic operation oil in these.Sight in view of environment Point, preferably low PCA operation oil.In order to obtain preferable cryogenic property and outstanding ice snow performance, preferably paraffin operation oil.Stone Wax operation oil object lesson include all purchased from Idemitsu Kosen Co., Ltd. (Idemitsu KosanCo.Ltd.) PW-90, PW-150 and PS-32.

At rubber composition in the case of the tread cap of summer tire, relative to the rubber components of every 100 mass parts, More than amount preferably 1 mass parts of oil, more than more preferably 2 mass parts.Below amount further preferably 30 mass parts of oil, more preferably 20 mass Below Fen.When this amount falls within the above-described range, while good workability is provided, it is also possible to obtain outstanding fuel economy Property and outstanding wet earth-catching property.

At rubber composition in the case of the tread cap without the anti-skidding winter tire of nail, relative to every 100 mass parts Rubber components, more than amount preferably 5 mass parts of oil, more than more preferably 10 mass parts, more than 15 mass parts.When this amount Less than 5 mass parts, it is difficult to produce the effect improving ice snow performance fully.Below amount further preferably 100 mass parts of oil, more excellent Select below 80 mass parts, below 50 mass parts.When this amount is more than 100 mass parts, wearability can be reduced, go forward side by side One step reduces anti-reversion.

At rubber composition in the case of tread base, relative to the rubber components of every 100 mass parts, the amount of oil is excellent Select more than 1 mass parts, more than more preferably 3 mass parts.Below amount further preferably 20 mass parts of oil, below more preferably 10 mass parts. When equivalent falls within the above-described range, it is possible to obtain good processability.

In addition to the materials noted above, the rubber composition of the present invention can be suitably added in tire industry normally used Various materials, such as zinc oxide, stearic acid, various antioxidant, the plasticizer (such as, wax) in addition to oil, vulcanizing agent (example As, sulfur, organic peroxy agent) and vulcanization accelerator (such as, sulfenamide vulcanization accelerator, guanidine vulcanization accelerator).

The rubber composition of the present invention can be produced by known method, such as, by such as opening by rubber kneader device Put formula roll mill or banbury mixers mediates mentioned component, then by the mixture sulfuration through mediating.

The rubber composition of the present invention can be particularly well in the tyre surface (tread cap or tread base) of tire Use.Tread cap refers to the extexine of multilamellar tyre surface, and it contacts with ground, and tread base refers to the interior of multilamellar tyre surface Layer.Specifically, tread base is such as institute in Fig. 1 of Fig. 1 or JP 2008-303360 A of JP 2008-285682 A Show assembly.

The pneumatic tire formed by the rubber composition of the present invention can use above-mentioned rubber composition to be produced by common method Raw.Specifically, before sulfuration, the rubber composition optionally adding additive is extruded as the shape of tyre assembly such as tyre surface Shape, and assemble with other tyre assembly in conventional manner on tyre building machine, thus build unvulcanized tire.Take turns unvulcanized Tire heats pressurization in vulcanizer, thus produces pneumatic tire.

The pneumatic tire of the present invention is applicable to passenger car, card tire and the summer tire of bus (heavy-duty vehicle) or nothing Follow closely anti-skidding winter tire.

Embodiment

The present invention will be described in detail with reference to following example, but the invention is not restricted to these embodiments.

Chemicals in embodiment is listed in as follows.

Fresh latex: purchased from the fresh latex of Muhibbah Lateks company

EMAL E-27C (surfactant): purchased from the EMALE-27C (polyoxyethylene lauryl ether of Kao Corp Sodium sulfate, active component: 27 mass %)

NaOH: purchased from the NaOH of Wako Pure Chemical Industries, Ltd.

Wingstay L (antioxidant): purchased from Eliokem company Wingstay L (ρ-cresol and bicyclopentadiene Butylation condensation substance)

Emulvin W (surfactant): purchased from the Emulvin W (fragrance polyglycol ether) of Lanxess company

Tamol NN 9104 (surfactant): purchased from the Tamol NN 9104 (sodium of LOMAR PWA EINECS 246-676-2/formaldehyde of BASF AG Salt)

Van gel B (surfactant): purchased from Van gel B (Ervasil (Godecke)) of Vanderbilt company

NR:TSR 20

SBR: purchased from Buna VSL 2525-0 (styrene-content: 25 mass %, the contents of ethylene 25 of Lanxess company Quality %)

BR: purchased from the BR150B (cis-content: 97 mass %, ML of Ube Industries, Ltd₁₊₄(100 DEG C): 40,5% It is dissolved in the solution viscosity (25 DEG C) of toluene: 48cps, Mw/Mn:3.3)

White carbon black 1: purchased from DIABLACKI (ISAF, the N of Mitsubishi chemical Co., Ltd₂SA:114m²/ g, mean diameter: 23nm, DBP oil absorption: 114mL/100g)

White carbon black 2, purchased from Shoblack N330 (HAF, the N of Cabot Japan Co., Ltd.₂SA:75m²/g)

Silicon dioxide: purchased from the Ultrasil VN3 (N of Degussa company₂SA:175m²/g)

Silane coupler 1: purchased from NXT silane (the 3-Octanoylthio of Momentive Performance Materials Propyl-triethoxysilicane)

Silane coupler 2: purchased from the Si69 (double (3-triethoxysilylpropyltetrasulfide) tetrasulfide) of Degussa company

Oil 1: purchased from the Viva Tec 400 (TDAE) of H&R company

Oil 2: purchased from the PS-32 (paraffin operation oil) of Idemitsu Kosen Co., Ltd.

Wax: purchased from the Ozoace 0355 of fine wax Co., Ltd. of Japan

Zinc oxide: purchased from the zinc oxide #2 of Mitsu Mining & Smelting Co., Ltd

Stearic acid: purchased from the stearic acid pearl " Tsubaki " of Japan Oil Co

Antioxidant: purchased from Nocrac 6C (N-phenyl-N '-(1, the 3-diformazan of Ouchi Shinko Chemical Ind Co., Ltd. Base butyl) p-phenylenediamine, 6PPD)

Sulfur 1: purchased from the powder sulfur of He Jian chemical industry Co., Ltd.

Sulfur 2: purchased from the Seimi sulfur (oil content: 10%) of Qian Liu Industrial Co., Ltd of Japan

Vulcanization accelerator 1: purchased from the Nocceler NS of Ouchi Shinko Chemical Ind Co., Ltd.

Vulcanization accelerator 2: purchased from the Soxinol D of Sumitomo Chemical Co

(preparation of antioxidant dispersion)

Use ball mill, by Tamol NN 9104, the 12.5g of the water of 462.5g Yu Emulvin W, 12.5g of 12.5g The Wingstay L (total amount of mixture is 1000g) of Van gel B and 500g mix 16 hours, thus prepare antioxygen Agent dispersion.

(manufacturing example 1)

The solid concentration (DRC) of fresh latex is adjusted to 30% (w/v).Then, by the latex of 1000g with 25g's 10% aqueous solution of EMAL E-27C and the 25%NaOH aqueous solution of 60g, and by little for mixture at room temperature saponification 24 Time, thus prepare saponification caoutchouc latex.Then, add 6g antioxidant dispersion, and stir mixture 2 hours, so Rear interpolation water dilution mixture thing further, until rubber concentrations reaches 15% (w/v).Subsequently, with being slowly stirred interpolation formic acid, Thus pH is adjusted to 4.0.Subsequently, add cation polymeric flocculant, and stir mixture 2 minutes, in order to occur solidifying Knot.The diameter of thus obtained concretion (condensation rubber) is about 0.5～5mm.Concretion is taken out, and is at room temperature soaked Stain in the aqueous sodium carbonate of 2 mass % of 1000mL 4 hours, then, takes out rubber.Rubber mixes with the water of 2000mL, And stir mixture 2 minutes, be dehydrated the most as far as possible.This operation circulation is repeated 7 times.Subsequently, add the water of 500mL, and add Add the formic acid of 2 mass % until pH reaches 4, subsequently standing mixt 15 minutes.Then, mixture is dehydrated as far as possible, and again Secondary mix with water, be subsequently agitated for 2 minutes.This operation circulation is repeated 3 times.Then, with squeeze roll(s) by water from the rubber obtained Extrusion, thus rubber is formed thin slice, it is dried 4 hours at 90 DEG C subsequently.By this way, solid rubber is prepared (highly The natural rubber A of purification).

(manufacturing example 2)

As manufactured in example 1, manufacture solid rubber (highly purified natural rubber B), except for the difference that add 2 matter The formic acid of amount % is until pH reaches 1.

(comparing manufacture example 1)

The solid concentration (DRC) of fresh latex is adjusted to 30% (w/v).Then, by the latex of 1000g with 25g's 10% aqueous solution of EMAL E-27C and the 25%NaOH aqueous solution of 60g, and by little for mixture at room temperature saponification 24 Time, thus prepare saponification caoutchouc latex.Then, add 6g antioxidant dispersion, and stir mixture 2 hours, so Rear interpolation water dilution mixture thing further, until rubber concentrations reaches 15% (w/v).Subsequently, add formic acid under slow stirring, Thus pH is adjusted to 4.0.Subsequently, add cation polymeric flocculant, and stir mixture 2 minutes, in order to occur solidifying Knot.The diameter of thus obtained concretion (condensation rubber) is about 3～15mm.Concretion is taken out, and is immersed at room temperature In the aqueous sodium carbonate of 2 mass % of 1000mL 4 hours, then, take out rubber.Rubber is mixed with the water of 1000mL, and And stir mixture 2 minutes, it is dehydrated the most as far as possible.This operation is carried out once.Subsequently, add the water of 500mL, and add 2 matter The formic acid of amount %, until pH reaches 4, is subsequently agitated for 15 minutes.Then, mixture is dehydrated as far as possible, and again mixes with water, It is subsequently agitated for 2 minutes.This operation circulation is repeated 3 times, and is dried 4 hours subsequently at 90 DEG C.By this way, solid rubber is prepared Glue (highly purified natural rubber C).

(comparing manufacture example 2)

Solid rubber (highly purified natural rubber D) is manufactured, except for the difference that, with sodium carbonate as manufactured example 1 After aqueous solution carries out processing and be repeated 7 times water washing, with squeeze roll(s) rubber from rubber extruding thus formed by water thin slice it Before, the rubber obtained is without undergoing the acid treatment carried out with the formic acid of 2 mass %.

(manufacturing example 3)

By high ammonia latex commercially available on market, (purchased from Malay MUHIBBAH LATEKS company, solid rubber contains Amount: 62.0%) it is diluted with the sodium naphthenate saline solution of 0.12%, thus solid rubber content is adjusted to 10%.This Outward, add sodium dihydrogen phosphate thus pH is adjusted to 9.2.Relative to the rubber content of every 10g, it is added to the egg of 0.87g White hydrolytic enzyme (2.0M alkaline protease).Then, again pH is adjusted to 9.2, and the mixture generated is maintained at 37 At DEG C 24 hours.

Then, by after completing ferment treatment obtain latex and 1% nonionic surfactant (with trade name EMULGEN 810 is purchased from Kao Corp) aqueous solution, thus rubber concentrations is adjusted to 8%.Turning with 11000rpm Speed centrifugal mixture 30 minutes.Then, the paste components obtained by centrifugal treating is dispersed in EMULGEN 810 water of 1% In solution, thus rubber concentrations being adjusted to 8%, the rotating speed with 11000rpm carries out the centrifugal treating of 30 minutes again subsequently. This operation circulation is repeated 2 times.The paste components obtained is dispersed in distilled water, thus preparing solid rubber content is 60% Deproteinizing rubber latex.

The formic acid of 2 mass % is added, until pH reaches 4 to latex.Add cation polymeric flocculant further, in order to Obtain the rubber grain of 0.5～5mm.They are dehydrated as much as possible, and the rubber content relative to every 10g, add 50g's Water, adds the formic acid of 2 mass % subsequently, until pH reaches 3.After 30 minutes, take out rubber and use crepe machine to form thin slice, with After at 90 DEG C be dried 4 hours.By this way, solid rubber (highly purified natural rubber E) is prepared.

(manufacturing example 4)

As manufactured in example 3, manufacture solid rubber (highly purified natural rubber F), except for the difference that, add 2 matter The formic acid of amount % is until pH reaches 1.

(comparing manufacture example 3)

Then, by after completing ferment treatment obtain latex and 1% nonionic surfactant (with trade name EMULGEN 810 is purchased from Kao Corp) aqueous solution, thus rubber concentrations is adjusted to 8%.Turning with 11000rpm Speed centrifugal mixture 30 minutes.Then, the paste components obtained by centrifugal treating is dispersed in EMULGEN 810 water of 1% In solution, thus rubber concentrations being adjusted to 8%, the rotating speed with 11000rpm carries out the centrifugal treating of 30 minutes again subsequently. Again repeat this operation circulation.The paste components obtained is dispersed in distilled water, thus prepares solid rubber content and be The deproteinizing rubber latex of 60%.

The formic acid of 50 mass % is added in latex, until Cure of Rubber.Take out the rubber of solidification, and washing with water Use crepe machine to be formed thin slice simultaneously, be dried 4 hours at 90 DEG C subsequently.By this way, solid rubber is prepared (high The natural rubber G of degree purification).

(comparing manufacture example 4)

Solid rubber (highly purified natural rubber H) is manufactured, except for the difference that: in solidification as compared manufacture example 3 Rubber be removed after, in the aqueous sodium carbonate of 0.5 mass % impregnate 1 hour, then make while washing with water With crepe machine, rubber is formed thin slice, be dried 4 hours at 90 DEG C subsequently.

Solid rubber fabricated as described above is assessed as follows.Result is as shown in table 1.

By the rubber dicing manufactured by 5g, in order to the three-dimensional dimension of each add up to below 5mm (about 1-2mm × About 1-2mm × about 1-2mm).Sheet is placed in the beaker of 100mL, and at room temperature mixes with the distilled water of 50mL.By content Go through 2 minutes and be heated to 90 DEG C, irradiate 13 minutes (amounting to 15 minutes) with microwave (300W) subsequently, temperature adjusted simultaneously and protect Hold at 90 DEG C.Then, use ice bath by produced dipping water cooling to 25 DEG C after, with pH meter measure dipping water pH.

(acetone extract (preparation of sample))

Each solid rubber is cut into subtly the square coupons of 1mm, and weighs the sample of about 0.5g.By sample in Impregnate 48 hours in the acetone of 50g under room temperature (25 DEG C).Then, rubber taken out and be dried.Thus, sample is prepared (from it Middle extraction antioxidant).

(mensuration)

Measure the nitrogen content of sample by the following method.

Trace nitrogen/carbon analyzer " SUMIGRAPH NC 95A (firmly fractional analysis Service Co., Ltd) " is used to decompose and gasify Acetone extract sample obtained as described above, and, produced gas uses gas chromatograph " GC-8A (Shimadzu Seisakusho Ltd.'s strain formula Commercial firm) " it is analyzed, so that it is determined that nitrogen content.

ICP emission spectrometer (P-4010, Hitachi, Ltd) is used to measure phosphorus content.

Raw rubber is cut into the coupons of 1mm × 1mm, and the sample of accurate weighing about 70mg.It is added to 35mL Toluene, and at place cold, dark by mixture stand one week.Subsequently, centrifugal mixture, so that by the gel group insoluble in toluene Fractional precipitation, and remove the supernatant dissolving in toluene.By methanol only curing gel component, then it is dried.Measure xerogel The quality of component.Gel content (quality %) is determined by below equation:

Gel content (quality %)=(dried quality (mg))/(initial mass (mg) of sample) × 100.

<heat-resistant aging>

Before and after keeping 18 hours at 80 DEG C, measure solid rubber at 130 DEG C according to JIS K 6300:2001-1 Under Mooney viscosity ML (1+4).Heat-proof aging sex index is calculated by above-mentioned equation.

[table 1]

Table 1 show modified natural rubber that pH scope is 2～7 on heat-resistant aging than pH above-mentioned extraneous rubber Glue is outstanding.

(unvulcanized rubber composition and the preparation of test tire)

According to the formula as shown in table 2～4, the chemicals in addition to sulfur and vulcanization accelerator is used 1.7L Banbury Mixing roll is mediated.Then, with roller, sulfur and vulcanization accelerator are mediated with kneaded mixture, thus manufacture unvulcanized rubber Glue composition.Unvulcanized rubber composition is configured to the shape of tread cap or tread base, and on tyre building machine Assemble with other tyre assembly, thus manufacture unvulcanized tire.Carry out vulcanizing at 170 DEG C 10 minutes by unvulcanized tire, from And prepare test tire (size: 195/65R15, passenger car with summer tire (tread cap or tread base) or without nail anti-skidding Winter tire (tread cap).Unvulcanized rubber composition produced above and test tire are performed as follows assessment.Result As shown in table 2～4.Comparative example 1-1,2-1 and 3-1 are set to the reference comparative example in each form.

The Mooney viscosity of unvulcanized rubber composition measures at 130 DEG C according to JIS K 6300.Setting with reference to comparative example In the case of being set to 100, Mooney viscosity ML (1+4) value uses following formula to be expressed as index.Index the highest expression Mooney viscosity is the lowest And processability is the best.

(processability index)=(ML with reference to comparative example₁₊₄The ML of)/(each formula₁₊₄)×100

Use rolling resistance test machine, by running peace with intrinsic pressure, the load of 3.43kN of 230kPa, the speed of 80km/h Be contained on 15 × 6JJ wheel rim respectively tests tire, carrys out the resistance to rolling of determination test tire.It is being set as 100 with reference to comparative example In the case of, result is expressed as index.Index the highest expression result the best (fuel economy is the best).

Each group of test tire is arranged on all of car (Japan manufactures for preposition engine, front-wheel-drive cars, 2000cc) On wheel, and measure on moist asphalt roads the braking distance by 100km/h initial velocity.Result is expressed as referring to Number.The wet and slippery performance of the highest expression of index (wet earth-catching property) is the best.Following formula is used to determine index:

Wet and slippery performance=(with reference to the braking distance of comparative example)/(braking distance of each formula) × 100.

The performance on ice of vehicle-mounted test tire is estimated under the following conditions.Test tire is arranged on day The preposition engine of the 2000cc discharge capacity of this manufacture, rear wheel drive automobile on.This experiment is in the sumitomo rubber work of Hokkaido, Japan The test tracks (on ice) of the rising sun river tyre proving ground of industry Co., Ltd. is carried out.Temperature is-6 DEG C～1 DEG C on ice.

Braking ability (brakes stop distance) on ice: testing stop distance on ice, described stop distance on ice is at 30km/ Required separation distance is stopped after applying under h to pin brake.In the case of being set as 100 with reference to comparative example, result uses following formula to represent For index.Index the highest expression braking ability on ice is the best.

(index of earth-catching property on ice)=(with reference to the stop distance of comparative example)/(stop distance of each formula) × 100

Each group of test tire is arranged on the automobile of the preposition engine of Japan's manufacture, front-wheel drive.At 8000km mileage After, measure the groove depth of tire face.Calculate distance during tire groove depth reduction 1mm, and use following formula to be expressed as index.Index The biggest expression wearability is the best.

(abrasion resistance index)=(the tire groove depth of each formula reduces distance during 1mm)/(tire groove depth with reference to comparative example Reduce distance during 1mm) × 100

Test tire is arranged on all wheels of automobile (Japan manufactures for preposition engine, the automobile of front-wheel drive, 2000cc) On.Test drive person drives vehicle, and subjective evaluation control stability in test tracks.Assess with 1-10 level as standard, Wherein 10 is optimal.The control stability of test tire is estimated relative to the reference comparative example being appointed as at 6.Count the highest Represent that control stability is the best.

[table 2]

The Rubber composition for cap tread of summer tire

[table 3]

Without following closely the Rubber composition for cap tread of anti-skidding winter tire

[table 4]

Rubber composition for base tread

Result in table 1～4 confirms: even at the highly purified natural rubber using pH to be 2～7 and specific silane In the embodiment of the combination of connection agent, it is thus achieved that in performance such as fuel economy, processability, heat-resistant aging, wearability, wet grab Notable and the improvement of equilibrium in ground performance, ice snow performance and control stability.

Claims (according to the amendment of treaty the 19th article)

1. a rubber composition for tire, it comprises:

PH is adjusted to 2～7 and highly purified modified natural rubber that phosphorus content is below 200ppm；

At least one in white carbon black or white filler；And

Silane coupler shown in following formula (S1):

Wherein, R¹⁰⁰¹Represent selected from the univalent perssad of lower group :-Cl ,-Br ,-OR¹⁰⁰⁶,-O (O=) CR¹⁰⁰⁶,-ON= CR¹⁰⁰⁶R¹⁰⁰⁷,-ON=CR¹⁰⁰⁶R¹⁰⁰⁷、-NR¹⁰⁰⁶R¹⁰⁰⁷And-(OSiR¹⁰⁰⁶R¹⁰⁰⁷)_h(OSiR¹⁰⁰⁶R¹⁰⁰⁷R¹⁰⁰⁸), wherein, R¹⁰⁰⁶、R¹⁰⁰⁷And R¹⁰⁰⁸Being same to each other or different to each other, and each represent hydrogen atom or C1-C18 monovalent hydrocarbon, h represents flat Average is the numeral of 1～4；R¹⁰⁰²Represent R¹⁰⁰¹, hydrogen atom, or C1-C18 monovalent hydrocarbon；R¹⁰⁰³Represent R¹⁰⁰¹、R¹⁰⁰², hydrogen atom, Or group :-[O (R¹⁰⁰⁹O)_j]_0.5-, wherein, R¹⁰⁰⁹Representing C1-C18 alkylidene, j represents the integer of 1～4；R¹⁰⁰⁴Represent C1- C18 bivalent hydrocarbon radical；R¹⁰⁰⁵Represent C1-C18 monovalent hydrocarbon；And x, y and z are the numeral meeting following relation: x+y+2z= 3,0≤x≤3,0≤y≤2, and 0≤z≤1.

2. rubber composition for tire as described in claim 1, it is characterised in that

Described modified natural rubber is by removing nonrubber composition in natural rubber, being processed to acid compound subsequently Obtain, and

The pH of described modified natural rubber is 2～7.

3. rubber composition for tire as described in claim 1, it is characterised in that

Described modified natural rubber processes scrubbed saponification sky by washing saponification caoutchouc latex and with acid compound So elastomer latex obtains, and

The pH of described modified natural rubber is 2～7.

4. rubber composition for tire as described in claim 1, it is characterised in that

Described modified natural rubber processes scrubbed de-egg by washing deproteinized natural rubber latex and with acid compound White caoutchouc latex obtains, and

The pH of described modified natural rubber is 2～7.

5. the rubber composition for tire as according to any one of Claims 1 to 4, it is characterised in that

The nitrogen content of described modified natural rubber is below 0.15 mass %.

6. the rubber composition for tire as according to any one of Claims 1 to 5, it is characterised in that

Described pH measures by the following method: described modified natural rubber cuts into the square print of every limit at most 2mm, by institute State print to be immersed in distilled water, the print impregnated with microwave irradiation, to carry out extracting at 90 DEG C 15 minutes, and use pH meter Measure produced dipping water.

7. the rubber composition for tire as according to any one of claim 1～6, it is characterised in that

The heat-proof aging sex index of described modified natural rubber is 75～120%, and described heat-proof aging sex index is by such as the following Formula is defined based on the Mooney viscosity ML (1+4) at 130 DEG C measured according to JIS K6300:2001-1,

Heat-proof aging sex index (%)=(Mooney viscosity of the modified natural rubber that heat treatment measured after 18 hours at 80 DEG C)/ (Mooney viscosity of the modified natural rubber before heat treatment) × 100.

8. the rubber composition for tire as according to any one of claim 1～7, it is characterised in that

Described white filler is silicon dioxide.

9. the rubber composition for tire as according to any one of claim 1～8, wherein, described rubber composition for tire Comprise SBR styrene butadiene rubbers or polybutadiene rubber.

10. the rubber composition for tire as according to any one of claim 1～9, it is characterised in that

Described modified natural rubber prepares without mastication.

11. 1 kinds of pneumatic tires, it is formed by the rubber composition for tire according to any one of claim 1～10.

Illustrate or state (according to the amendment of treaty the 19th article)

1, with former claim 5 as foundation, in former claim 1, add technical characteristic " phosphorus content be 200ppm with Under "；

2, former claim 5 is deleted；

3, deletion according to claim 5, numbering and reference numerals to former claim 6-12 are made and correspondingly being revised.

Claims

1. a rubber composition for tire, it comprises:

PH adjusts the highly purified modified natural rubber of 2～7；

At least one in white carbon black or white filler；And

Silane coupler shown in following formula (S1):

Wherein, R¹⁰⁰¹Represent the univalent perssad selected from lower group :-Cl ,-Br ,-OR¹⁰⁰⁶,-O (O=) CR¹⁰⁰⁶,-ON=CR¹⁰⁰⁶R¹⁰⁰⁷,-ON=CR¹⁰⁰⁶R¹⁰⁰⁷、-NR¹⁰⁰⁶R¹⁰⁰⁷And-(OSiR¹⁰⁰⁶R¹⁰⁰⁷)_h(OSiR¹⁰⁰⁶R¹⁰⁰⁷R¹⁰⁰⁸), wherein, R¹⁰⁰⁶、R¹⁰⁰⁷And R¹⁰⁰⁸Being same to each other or different to each other, and each represent hydrogen atom or C1-C18 monovalent hydrocarbon, h represents the numeral that meansigma methods is 1～4；R¹⁰⁰²Represent R¹⁰⁰¹, hydrogen atom, or C1-C18 monovalent hydrocarbon；R¹⁰⁰³Represent R¹⁰⁰¹、R¹⁰⁰², hydrogen atom or group :-[O (R¹⁰⁰⁹O)_j]_0.5-, wherein, R¹⁰⁰⁹Representing C1-C18 alkylidene, j represents the integer of 1～4；R¹⁰⁰⁴Represent C1-C18 bivalent hydrocarbon radical；R¹⁰⁰⁵Represent C1-C18 monovalent hydrocarbon；And x, y and z are the numeral meeting following relation: x+y+2z=3,0≤x≤3,0≤y≤2, and 0≤z≤1.

Described modified natural rubber by removing nonrubber composition in natural rubber, being processed to obtain with acid compound subsequently, and

The pH of described modified natural rubber is 2～7.

Described modified natural rubber obtains by washing saponification caoutchouc latex and with the acid compound scrubbed saponification caoutchouc latex of process, and

The pH of described modified natural rubber is 2～7.

Described modified natural rubber obtains by washing deproteinized natural rubber latex and with the acid compound scrubbed deproteinized natural rubber latex of process, and

The pH of described modified natural rubber is 2～7.

The phosphorus content of described modified natural rubber is below 200ppm.

The nitrogen content of described modified natural rubber is below 0.15 mass %.

Described pH measures by the following method: described modified natural rubber cuts into the square print of every limit at most 2mm, described print is immersed in distilled water, the print impregnated with microwave irradiation, to carry out extracting 15 minutes at 90 DEG C, and measures produced steep water with pH meter.

The heat-proof aging sex index of described modified natural rubber is 75～120%, and described heat-proof aging sex index is defined based on the Mooney viscosity ML (1+4) at 130 DEG C measured according to JISK6300:2001-1 by below equation,

Heat-proof aging sex index (%)=(at 80 DEG C the Mooney viscosity of the modified natural rubber that heat treatment measured after 18 hours)/(Mooney viscosity of the modified natural rubber before heat treatment) × 100.

9. the rubber composition for tire as according to any one of claim 1～8, it is characterised in that

Described white filler is silicon dioxide.

10. the rubber composition for tire as according to any one of claim 1～9, wherein, described rubber composition for tire comprises SBR styrene butadiene rubbers or polybutadiene rubber.

11. the rubber composition for tire as according to any one of claim 1～10, it is characterised in that

Described modified natural rubber prepares without mastication.

12. a pneumatic tire, its rubber composition for tire according to any one of claim 1～11 is formed.